1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus, which forms an image on a recording medium in a state in which a cartridge including at least a developer containing part adapted to contain a developer to be applied to an electrophotographic photosensitive drum, is removably mounted to a main body of the electrophotographic image forming apparatus.
2. Description of the Related Art
Herein, the electrophotographic image forming apparatus (hereinafter, referred to as image forming apparatus) is a type in which an image is formed on a recording medium by using an electrophotographic image forming process. As the image forming apparatus, for example, there are given an electrophotographic copying machine, an electrophotographic printer (for example, color LED printer), a facsimile apparatus, and a word processor. Further, as the image forming apparatus, both of a black and white type and a color type are encompassed therein. Further, the recording medium is a type on which an image is formed by the electrophotographic image forming apparatus, and includes, for example, paper and an OHP sheet.
In general, a cartridge is, for example, a process cartridge or a developing cartridge, which is removably mounted to a main body of the electrophotographic image forming apparatus to contribute to an image forming process for forming an image on the recording medium. The process cartridge is constituted as a cartridge in which at least one of charging means, developing means, and cleaning means, which serve as process means acting on an electrophotographic photosensitive drum, is formed integrally with the electrophotographic photosensitive drum, and in which the thus formed cartridge is removably mounted to the main body of the electrophotographic image forming apparatus. Therefore, the process cartridge includes one which is constructed as a cartridge in which the developing means serving as the process means is formed integrally with the electrophotographic photosensitive drum, and in which the thus formed cartridge is removably mounted to the main body of the electrophotographic image forming apparatus. Further, the process cartridge includes one which is constructed as a cartridge in which the charging means, the developing means, or the cleaning means, which serve as the process means, are formed integrally with the electrophotographic photosensitive drum, and in which the thus formed cartridge is removably mounted to the main body. The process cartridge, which includes the electrophotographic photosensitive drum and the developing means formed integrally with each other, is referred to as a so-called integral type. Besides, the process cartridge, which includes the electrophotographic photosensitive drum and the process means other than the developing means formed integrally with each other, is referred to as a so-called separate type. In the process cartridge, the user him/herself may perform mounting and removing with respect to the main body. Therefore, the user may easily perform maintenance for the main body. Further, the developing cartridge includes a developing roller, contains developer (toner) which is used for developing an electrostatic latent image formed on the electrophotographic photosensitive drum by the developing roller, and is removably mounted to the main body. In a case of the developing cartridge, the electrophotographic photosensitive drum is attached to the main body or a cartridge-support member. Alternatively, the electrophotographic photosensitive drum is provided to the so-called separate type process cartridge (in this case, the process cartridge does not include the developing means). Also in the developing cartridge, the user him/herself may perform mounting and removing with respect to the main body of the image forming apparatus. Therefore, the user may easily perform maintenance for the main body. Thus, as the cartridge, the so-called integral type or the so-called separate type process cartridge is incorporated therein. Further, there is included as the cartridge a case in which the so-called separate type process cartridge and the developing cartridge are used in a pair. Further, as the cartridge, the electrophotographic photosensitive drum is securely attached to the main body or the cartridge-support member. Then, there is included a case in which the developing cartridge is capable of acting on the electrophotographic photosensitive drum, and is removably mounted to the cartridge-support member.
In the present invention, the cartridge includes at least a developer containing part adapted to contain a developer to be applied to an electrophotographic photosensitive drum, (hereinafter, referred to as drum), and is used by being removably mounted to a main body.
In order to attain downsizing of the image forming apparatus, there are cases of using, as the exposure apparatus of the drum, light emitting devices, which are provided in line in a longitudinal direction (rotation axis direction) of the drum, and which include multiple light emitting portions that illuminate in association with image information, for exposing the photosensitive drum. As a typical example of such light emitting devices, there is given an LED head array. For example, in an LED printer, which uses the LED head array as the exposure apparatus, it is constructed such that the luminance devices expose in accordance with image information signal sent from a controller, and the exposed light beams are converged by a lens to be formed on the drum as an image. Further, Japanese Patent Application Laid-open No. 2009-23281 discloses such a construction that the distance between the lens surface and the drum surface is adjusted by the eccentric cam. In this construction, the distance between the lens surface and the drum surface may be adjusted with precision. In addition, the distance between the lens surface and the drum surface may be adjusted through only the rotation of the eccentric cam, thereby being capable of simplifying the operation for adjustment. Further, the fixation of the eccentric cam after the adjustment is carried out by an adhesive.
In the related art image forming apparatus described above, it is required to make the distance between the surface of the lens and the surface of the drum be close very much. Besides, when the cartridge was shipped while being packed together into the main body of the image forming apparatus, similarly, the distance between the surface of the lens and the surface of the drum becomes extremely closer. For that reason, if a mechanical shock is applied to the image forming apparatus during the transportation, there is such a fear that the lens and the drum may be brought into contact with each other.
In addition, in the related art image forming apparatus, through the abutment of the abutment surface provided on the drum and the outer peripheral surface of the eccentric cam, the positioning of the distance between the surface of the lens and the surface of the drum is carried out. When the image forming apparatus was shipped while the cartridge is packed together into the main body, the abutment surface of the drum and the outer peripheral surface of the eccentric cam are brought into a contact state. For that reason, when a mechanical shock is applied to the image forming apparatus during the transportation, the abutment portion for positioning is also added with the strong mechanical shock. As described above, the fixation of the eccentric cam after the adjustment is carried out by an adhesive. However, there is such a fear that the positioning by the abutment as described above may vary when the strong shock is applied to the image forming apparatus during the transportation. As a result, displacement of a focal position may cause, and there is a fear of generating an image failure thereby. Accordingly, it is conceivable to take such a countermeasure of enlarging a wrapping material so that a mechanical shock applied to the image forming apparatus during the transportation may be mitigated.